Yang K, Mu X S, Xue J J, Perez-Polo J R, Hayes R L
Department of Neurosurgery, University of Texas Health Sciences Center at Houston 77030, USA.
J Neurosci Res. 1995 Nov 1;42(4):571-8. doi: 10.1002/jnr.490420415.
Lesion-induced increases in NGF mRNA are thought to be mediated by c-fos gene expression. Conversely, NGF induction of c-fos expression has been reported following administration of exogenous NGF. However, the relationship between c-fos and NGF gene expression after traumatic injury to the intact brain is not known. Thus, we applied in situ hybridization and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) methods to determine temporal profiles of c-fos and NGF mRNA expression in rat brains after controlled impact to the exposed cortex. Using alternate sections from the same rat brains, in situ hybridization studies showed that in neocortex, c-fos mRNA transiently increased at 30 min, 1 hr, and 3 hr after injury, while there were no increases of NGF mRNA at these postinjury time points. In the hippocampus, in situ hybridization showed that c-fos mRNA increased at 30 min, 1 hr and 3 hr postinjury, while NGF mRNA increased at 1 hr, 3 hr but not at 30 min after injury. RT-PCR studies in hippocampus confirmed that c-fos mRNA increased as early as 5 min after injury, peaked at 30 min postinjury, and remained elevated 5 hr postinjury. Levels of hippocampal NGF mRNA expression increased by 1 hr after injury and plateaued until 3 and 5 hr postinjury. These data are consistent with the possible regulatory role of endogenous c-fos on NGF expression following traumatic brain injury.
损伤诱导的NGF mRNA增加被认为是由c-fos基因表达介导的。相反，在外源性NGF给药后，已有报道称NGF可诱导c-fos表达。然而，完整大脑创伤性损伤后c-fos与NGF基因表达之间的关系尚不清楚。因此，我们应用原位杂交和半定量逆转录聚合酶链反应（RT-PCR）方法，以确定在对暴露的皮质进行控制性撞击后，大鼠大脑中c-fos和NGF mRNA表达的时间变化情况。利用来自同一只大鼠大脑的交替切片，原位杂交研究显示，在新皮质中，c-fos mRNA在损伤后30分钟、1小时和3小时短暂增加，而在这些损伤后时间点NGF mRNA没有增加。在海马体中，原位杂交显示c-fos mRNA在损伤后30分钟、1小时和3小时增加，而NGF mRNA在损伤后1小时、3小时增加，但在30分钟时不增加。海马体的RT-PCR研究证实，c-fos mRNA在损伤后5分钟就开始增加，在损伤后30分钟达到峰值，并在损伤后5小时仍保持升高。海马体NGF mRNA表达水平在损伤后1小时升高，并在损伤后3小时和5小时保持稳定。这些数据与内源性c-fos在创伤性脑损伤后对NGF表达可能的调节作用一致。
